A flexible all-carbon diamond photodetector and a preparation method thereof

Abstract

The application relates to the technical field of photoelectric detector preparation, and particularly provides a flexible full-carbon diamond photoelectric detector and a preparation method thereof. The method comprises the following steps: forming a patterned mask layer on a growth substrate; performing a crystal implantation treatment on the growth substrate to form a first seed layer on an exposed top surface area of the growth substrate; removing the patterned mask layer, and then growing a conductive carbon-based film on the top surface of the growth substrate based on the first seed layer; performing a secondary crystal implantation treatment on the growth substrate with the conductive carbon-based film to form a second seed layer on the top surface of the growth substrate and the surface of the conductive carbon-based film; growing a flexible diamond film on the top surface of the growth substrate and the surface of the conductive carbon-based film based on the second seed layer; and physically peeling the flexible full-carbon diamond detector from the growth substrate. The method can be used for preparing a flexible full-carbon diamond photoelectric detector which has good structural stability, a long service life, is green and pollution-free, has low preparation cost and high device yield.

Description

Technical Field

[0001] This application relates to the field of photodetector fabrication technology, and more specifically, to a flexible all-carbon diamond photodetector and its fabrication method. Background Technology

[0002] Existing diamond photodetectors still have significant defects and shortcomings in the fabrication of flexible, high-performance devices, specifically: First, existing diamond photodetectors use metal electrodes. Because the adhesion between the metal electrodes and the diamond surface is weak, the metal electrodes are prone to detachment or breakage during prolonged bending or exposure to temperature changes, ultimately leading to device failure and compromising the device's lifespan and reliability. Furthermore, metal electrodes have poor chemical stability. Under extreme environments such as high temperatures, strong acids and alkalis, or strong radiation, they are susceptible to oxidation, corrosion, or electromigration, undermining the inherent environmental resilience of diamond photodetectors and preventing them from fully utilizing the intrinsic environmental adaptability of diamond.

[0003] Secondly, existing preparation methods typically require first depositing a thick diamond film on a silicon wafer, and then completely etching away the silicon substrate using a mixture of hydrofluoric acid and nitric acid to obtain a flexible diamond film. The current mainstream method of obtaining flexible diamond films by etching the silicon substrate consumes large amounts of acid, making the process dangerous and environmentally polluting, which does not meet the requirements of green production development. Furthermore, the silicon substrate is completely etched and destroyed, making it unrecyclable and significantly increasing preparation costs. This method is unsuitable for mass production and hinders large-scale commercial applications. Therefore, this method suffers from overall process complexity and high cost.

[0004] Finally, in existing processes, electrodes are fabricated using photolithography and metal evaporation after the diamond film is grown. However, due to the large surface roughness of polycrystalline diamond, it is difficult to perform micron-level photolithography focusing directly on its surface, resulting in high processing difficulty. Furthermore, the metal layer is prone to fracture at the diamond grain boundaries, ultimately leading to a decrease in device yield and further increasing the manufacturing cost.

[0005] There is currently no effective technical solution to the above problems. Summary of the Invention

[0006] The purpose of this application is to provide a flexible all-carbon diamond photodetector and its fabrication method, which can produce a flexible all-carbon diamond photodetector with good structural stability, long service life, green and pollution-free, low fabrication cost and high device yield.

[0007] In a first aspect, this application provides a method for fabricating a flexible all-carbon diamond photodetector, which includes the following steps: S1. A patterned mask layer is formed on the growth substrate; the patterned mask layer is used to cover part of the top surface area of ​​the growth substrate and expose the remaining top surface area of ​​the growth substrate. S2. Perform a seeding process on the growth substrate to form a first seed layer in the exposed top surface area of ​​the growth substrate; S3. Remove the patterned mask layer, and then grow a conductive carbon-based thin film on the top surface of the growth substrate based on the first seed layer; S4. Perform a secondary seeding process on the growth substrate on which a conductive carbon-based thin film has been grown, so as to form a second seed layer on the top surface of the growth substrate and the surface of the conductive carbon-based thin film. S5. A flexible diamond film is grown on the top surface of the growth substrate and the conductive carbon-based surface based on the second seed layer; the flexible diamond film and the conductive carbon-based film form a flexible all-carbon diamond photodetector, and the bonding force between the flexible diamond film and the conductive carbon-based film is greater than the bonding force between the flexible diamond film and the growth substrate and the bonding force between the conductive carbon-based film and the growth substrate. S6. Physically peel the flexible all-carbon diamond detector from the growth substrate.

[0008] Optionally, step S1 includes: S11. The growth substrate is ultrasonically cleaned sequentially using acetone, anhydrous ethanol and deionized water, and then dried. S12. A patterned mask layer is formed on the growth substrate based on photolithography.

[0009] Optionally, step S12 includes: S121. Photoresist is spin-coated onto a growth substrate using a photoresist spin-coating process to form a photoresist layer on the growth substrate, and then the photoresist layer is cured. S122. Expose the cured photoresist layer using a preset photomask. S123. The exposed photoresist layer is developed, and then the developed photoresist layer is rinsed with deionized water and dried in sequence; the developed photoresist layer is a patterned mask layer.

[0010] Optionally, the specific process of step S2 is the same as that of step S4, and step S2 includes: S21. Immerse the growth substrate with the patterned mask layer into a nanodiamond suspension; the nanodiamond suspension is composed of nanodiamond particles and solvent, and the particle size of the nanodiamond particles is 5-10 nm. S22. The growth substrate that has entered the nanodiamond suspension is subjected to ultrasonic treatment for a preset duration to form a first seed layer in the exposed top surface area of ​​the growth substrate.

[0011] Optionally, step S3 includes: S31. Remove the graphical mask layer; S32. Using a first chemical vapor deposition process, a diamond film is grown on the top surface of the growth substrate based on the first seed layer, and diborane is introduced during the diamond film growth process to make the grown diamond film conductive, thereby forming a conductive carbon-based film on the top surface of the growth substrate.

[0012] Optionally, the reaction gases in the first chemical vapor deposition process are hydrogen and methane, with a methane to hydrogen gas flow rate ratio of 1%-5%, a diborane to methane ratio of 2000-10000 ppm, a growth gas pressure of 75 torr, and a growth temperature of 900℃.

[0013] Optionally, step S5 includes: S51. Using a second chemical vapor deposition process, diamond films are grown on the top surface of the growth substrate and the conductive carbon-based surface based on the second seed layer until the thickness of the diamond films grown on the top surface of the growth substrate and the conductive carbon-based surface reaches the preset thickness, so as to form a flexible diamond film on the top surface of the growth substrate and the conductive carbon-based surface.

[0014] Optionally, the reaction gases for the second chemical vapor deposition include oxygen, hydrogen, and methane, with a methane to hydrogen gas flow rate ratio of 0.5%-3%, a growth gas pressure of 75 torr for the second chemical vapor deposition process, a growth temperature of 900℃ for the second chemical vapor deposition process, and a preset thickness of 1-20 μm.

[0015] Optionally, step S6 includes: S61. Adhesive flexible carrier is attached to the surface of flexible diamond film; S52. Air bubbles between the flexible carrier and the flexible diamond film are expelled by gently pressing the flexible carrier. S53. Apply mechanical force to the flexible carrier to peel the flexible all-carbon diamond detector off the growth substrate.

[0016] Secondly, this application also provides a flexible all-carbon diamond photodetector, which is prepared by the flexible all-carbon diamond photodetector preparation method provided in the first aspect above.

[0017] As can be seen from the above, the flexible all-carbon diamond photodetector and its fabrication method provided in this application use an all-carbon structure to replace the traditional metal electrodes and a physical exfoliation process to replace the traditional chemical etching process. The process sequentially completes the steps of patterned mask preparation, crystal implantation, conductive carbon-based thin film growth, secondary crystal implantation, flexible diamond thin film growth, and physical exfoliation, thereby obtaining a structurally stable flexible all-carbon diamond photodetector. This method solves the problems of easy detachment and breakage of traditional metal electrodes and poor chemical stability, as well as the problems of high pollution, non-recyclable substrates, high cost, high processing difficulty, and low yield associated with traditional chemical etching methods. It has the advantages of good structural stability, long service life, green and pollution-free operation, low fabrication cost, high device yield, and can meet the requirements of flexible electronic devices that can be bent and deformed. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a method for fabricating a flexible all-carbon diamond photodetector, as provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0021] In a first aspect, this application provides a method for fabricating a flexible all-carbon diamond photodetector, which includes the following steps: S1. A patterned mask layer is formed on the growth substrate; the patterned mask layer is used to cover part of the top surface area of ​​the growth substrate and expose the remaining top surface area of ​​the growth substrate. S2. Perform a seeding process on the growth substrate to form a first seed layer in the exposed top surface area of ​​the growth substrate; S3. Remove the patterned mask layer, and then grow a conductive carbon-based thin film on the top surface of the growth substrate based on the first seed layer; S4. Perform a secondary seeding process on the growth substrate on which a conductive carbon-based thin film has been grown, so as to form a second seed layer on the top surface of the growth substrate and the surface of the conductive carbon-based thin film. S5. A flexible diamond film is grown on the top surface of the growth substrate and the conductive carbon-based surface based on the second seed layer; the flexible diamond film and the conductive carbon-based film form a flexible all-carbon diamond photodetector, and the bonding force between the flexible diamond film and the conductive carbon-based film is greater than the bonding force between the flexible diamond film and the growth substrate and the bonding force between the conductive carbon-based film and the growth substrate. S6. Physically peel the flexible all-carbon diamond detector from the growth substrate.

[0022] For ease of understanding, some key terms in this embodiment are explained below. The growth substrate in this embodiment is a base material used to support subsequent thin film growth. In this embodiment, a polished silicon wafer with high surface flatness and a crystal orientation of (100) is preferably used as the growth substrate. This silicon wafer has good mechanical strength and thermal stability. The patterned mask layer in this embodiment is a thin layer that forms a specific pattern on the surface of the growth substrate. Its function is to selectively cover part of the top surface area of ​​the growth substrate while exposing the remaining top surface area. This mask layer can be made of materials such as photoresist, and precise patterning is achieved through photolithography. The first and second seed layers of the seed layer in this embodiment are preferably both layer structures composed of nanodiamond particles. They provide nucleation points on the surface of the growth substrate or thin film, guiding the subsequent growth of the diamond thin film. The particle size of the nanodiamond particles is typically between 5-10 nm to ensure the uniformity and high density of the seed layer. The conductive carbon-based thin film of this embodiment is a carbon-based material thin film with conductive properties. In this embodiment, it serves as the electrode of a flexible all-carbon diamond photodetector. This film can be obtained by growing a diamond thin film using a chemical vapor deposition process. Dopants (such as boron) are introduced during the diamond thin film growth process to achieve conductivity. The flexible diamond thin film of this embodiment is a diamond thin film with a certain degree of flexibility. It, together with the conductive carbon-based thin film, constitutes a flexible all-carbon diamond photodetector. This film is grown using a chemical vapor deposition process. In this embodiment, the diamond thin film can achieve the required flexibility by controlling its thickness to 1-20 μm. The flexible all-carbon diamond photodetector of this embodiment is a photodetector composed of a conductive carbon-based thin film and a flexible diamond thin film. Since both the conductive carbon-based thin film and the flexible diamond thin film are composed of carbon elements, the detector has an all-carbon structure and can achieve flexible applications. Because the bonding force between the flexible diamond thin film and the conductive carbon-based thin film is greater than the bonding force between the flexible diamond thin film and the growth substrate, and the bonding force between the conductive carbon-based thin film and the growth substrate, this embodiment can utilize the difference in bonding force to separate the flexible all-carbon diamond photodetector from the growth substrate by physical peeling.

[0023] This application provides a method for fabricating a flexible all-carbon diamond photodetector, which includes the following steps: First, a patterned mask layer is formed on the growth substrate. This patterned mask layer covers part of the top surface area of ​​the growth substrate, leaving the remaining top surface area exposed. For example, a polished silicon wafer with high surface flatness can be selected as the growth substrate, and a negative image pattern of the interdigitated electrodes can be defined on it using photolithography. The specific process of step S1 can be as follows: spin-coating photoresist onto the cleaned silicon substrate; pre-baking and curing the photoresist; using a mask with the interdigitated electrode pattern (the pattern corresponding to the conductive carbon-based thin film), exposing it using an ultraviolet lithography machine, and developing the exposed photoresist layer; after development, rinsing with deionized water and drying to obtain the patterned mask layer, where the shape of the exposed area on the top surface of the silicon substrate corresponds to the interdigitated electrode pattern.

[0024] Next, the growth substrate undergoes a seeding process to form a first seed layer on the exposed top surface region of the growth substrate. For example, the growth substrate with a patterned mask layer can be immersed in a nanodiamond suspension composed of nanodiamond particles with a particle size of 5-10 nm and a solvent (such as DMSO (dimethyl sulfoxide) or ethanol). Subsequently, the growth substrate immersed in the nanodiamond suspension is subjected to ultrasonic treatment for a preset time (e.g., 10-30 minutes) to ensure that the nanodiamond particles are uniformly adsorbed on the photoresist surface and the exposed silicon substrate surface, thereby forming a nanodiamond seed layer (first seed layer) on the silicon wafer surface that is consistent with the mask pattern.

[0025] Next, the patterned mask layer is removed, and then a conductive carbon-based thin film is grown on the top surface of the growth substrate based on the first seed layer. For example, the processed silicon wafer is placed in the reaction chamber of a microwave plasma chemical vapor deposition (MPCVD) system to grow a highly conductive BDD thin film, with hydrogen as the carrier gas, methane as the carbon source, and diborane as the dopant source. By controlling the gas flow ratio, for example, the methane to hydrogen flow ratio is controlled at 1%-5%, and the diborane to methane ratio reaches a heavily doped level (2000-10000ppm), the grown diamond is ensured to have metallic conductivity. The growth conditions can be controlled at a gas pressure of approximately 75 torr, a stage temperature of 900°C, and microwave power adjusted according to the cavity size. A continuous and dense black boron-doped polycrystalline diamond layer is grown in the seed crystal region, serving as the ohmic contact electrode of the detector. It should be understood that in this embodiment, the diamond particles adsorbed on the photoresist surface are detached by removing the patterned mask layer, while the diamond particles directly adsorbed on the silicon substrate (the exposed area corresponding to the interdigitated pattern area on the top surface of the silicon substrate) are retained.

[0026] Subsequently, a flexible diamond film is grown on the top surface of the growth substrate and the conductive carbon-based surface based on the second seed layer. For example, the silicon wafer is placed back into the MPCVD reaction chamber to grow an undoped intrinsic diamond layer, with only hydrogen and methane as reaction gases. The methane concentration (CH4 / H2) is controlled at 0.5%-3%. The growth pressure, temperature, and power of the flexible diamond film can be similar to those of the conductive carbon-based film. MPCVD growth continues until the film reaches the desired thickness (e.g., 1µm-20µm) to make the diamond film flexible. This diamond film will cover the BDD electrode and fill the electrode gap.

[0027] Finally, the flexible all-carbon diamond detector is physically peeled off from the growth substrate. For example, after the flexible all-carbon diamond detector has cooled, a support medium with a certain degree of adhesion (such as heat-release tape, PDMS film, Kapton tape, or transparent PET tape) is taken out and flatly attached to the surface of the grown flexible diamond film. A uniform pulling force is applied to peel the tape along with the diamond film off the silicon substrate. Because the bonding force between the flexible diamond film and the conductive carbon-based film is greater than the bonding force between the flexible diamond film and the growth substrate, and also between the conductive carbon-based film and the growth substrate, the flexible all-carbon diamond detector can be completely peeled off from the growth substrate.

[0028] The following example provides a more detailed explanation of the above technical solutions: Suppose we need to fabricate a flexible all-carbon diamond photodetector for wearable devices to monitor ultraviolet light of a specific wavelength. Traditional diamond photodetectors are rigid structures, unsuitable for flexible electronics applications. Furthermore, they suffer from poor interface compatibility between the metal electrodes and diamond, leading to susceptibility to failure, light-shielding effects, and poor chemical stability. In addition, traditional chemical etching and stripping processes are hazardous, highly polluting, and result in non-recyclable substrates, high costs, and difficult device fabrication with low yields.

[0029] This application proposes a method for fabricating a flexible all-carbon diamond photodetector. First, a flat single-crystal silicon wafer is selected as the growth substrate. To subsequently form interdigitated electrodes, a patterned mask layer is formed on the silicon wafer using photolithography. Specifically, the silicon wafer is first ultrasonically cleaned and dried, then spin-coated with photoresist and cured. Next, the pre-designed interdigitated electrode pattern mask is exposed and developed. After development, the areas where the photoresist has been removed expose the silicon substrate; these areas will be used to grow conductive carbon-based thin films, while other areas remain covered by photoresist.

[0030] Subsequently, the silicon substrate with the patterned mask layer is subjected to a crystal implantation process. The silicon wafer is immersed in a suspension containing nanodiamond particles and then sonicated. Due to the covering effect of the photoresist, the nanodiamond particles are adsorbed onto the exposed areas of the silicon substrate, forming the first seed layer. Then, by dissolving the photoresist (removing the patterned mask layer), the nanodiamond particles adsorbed on the photoresist are detached. This step avoids the complexity of photolithography to fabricate electrodes after diamond growth, reducing the fabrication difficulty.

[0031] After removing the patterned mask layer, a conductive carbon-based thin film is grown on the top surface of a silicon substrate based on the first seed layer. The silicon wafer is placed in a microwave plasma chemical vapor deposition (MPCVD) system, and hydrogen, methane, and diborane are introduced. By precisely controlling the gas flow ratio and growth conditions, a conductive boron-doped polycrystalline diamond thin film is grown on the first seed layer, forming an interdigitated conductive carbon-based thin film. This conductive carbon-based thin film, as an all-carbon structure electrode, has better interface matching with the diamond photosensitive layer, solving the problems of poor adhesion and poor chemical stability of traditional metal electrodes.

[0032] To grow a continuous probe layer film on and between the conductive electrodes, a secondary seeding process is performed on the silicon substrate with the grown conductive carbon-based film. Specifically, the silicon substrate with the grown conductive carbon-based film is immersed in a nanodiamond suspension and ultrasonically treated, causing nanodiamond particles to uniformly adhere to the surface of the conductive carbon-based film and the exposed silicon surface between the conductive carbon-based film, forming a second seed layer. This provides a nucleation basis for the subsequent continuous growth of the intrinsic diamond film.

[0033] Based on the second seed layer, a flexible diamond film is grown on the top surface of a silicon substrate and the surface of a conductive carbon-based substrate. The silicon wafer is then placed back into the MPCVD reaction chamber, and hydrogen and methane are introduced to grow an undoped intrinsic diamond layer. By controlling the growth parameters and growth time, the diamond film reaches a preset thickness, such as 5 μm. This diamond film covers and fills the gaps between the conductive carbon-based films, forming a continuous flexible diamond film. Since the silicon substrate in this embodiment has not undergone surface roughening treatment, the adhesion between the flexible diamond film and the conductive carbon-based film is greater than the adhesion between the flexible diamond film and the growth substrate, as well as the adhesion between the conductive carbon-based film and the growth substrate, thus creating conditions for subsequent physical peeling.

[0034] Finally, the flexible all-carbon diamond detector is physically peeled off from the growth substrate. After the flexible all-carbon diamond detector cools, a flexible, adhesive carrier (e.g., heat-release tape) is smoothly attached to the surface of the flexible diamond film, and air bubbles are gently pressed out. Then, a uniform mechanical force is applied to the flexible carrier to peel the tape along with the diamond film off the silicon substrate. Because the adhesion between the flexible diamond film and the conductive carbon-based film is greater than the adhesion between the flexible diamond film and the growth substrate, and also greater than the adhesion between the conductive carbon-based film and the growth substrate, complete physical peeling of the flexible all-carbon diamond detector can be achieved.

[0035] As can be seen from the above examples, the method for fabricating flexible all-carbon diamond photodetectors proposed in this application demonstrates significant advantages and innovations in several key technical aspects.

[0036] Firstly, regarding device fabrication, this method pre-forms a patterned mask layer on the growth substrate and utilizes crystal implantation to achieve localized growth of conductive carbon-based thin films. This contrasts with the traditional method of performing photolithography and metal evaporation to fabricate electrodes after the diamond thin film growth is complete. Specifically, due to the large surface roughness of polycrystalline diamond, photolithography focusing is difficult, and the metal layer is prone to breakage at grain boundaries, resulting in low device yield using traditional methods. This application, by pre-defining the electrode area, avoids the challenge of micron-level photolithography on a rough diamond surface, significantly reducing fabrication difficulty and improving device yield.

[0037] Secondly, regarding the selection of electrode materials, this method uses conductive carbon-based thin films instead of traditional metal electrodes. Traditional metal electrodes such as gold, aluminum, platinum, or titanium have poor interfacial compatibility and weak adhesion with diamond, making them prone to detachment or breakage when the device is bent or heated. Furthermore, metal electrodes exhibit poor chemical stability under extreme environments. In contrast, this application uses a fully carbon-structured conductive carbon-based thin film as the electrode, which has better compatibility and adhesion with the diamond photosensitive layer. This solves the problems of easy detachment and poor chemical stability of metal electrodes, while retaining the advantages of diamond's resistance to harsh environments, thus improving the reliability and performance of the device.

[0038] Furthermore, regarding the flexibility process, this method employs physical peeling to separate the flexible all-carbon diamond detector from the growth substrate. This contrasts sharply with the current mainstream method of obtaining flexible diamond films through chemical etching of silicon substrates. Chemical etching requires large amounts of acid, is hazardous and environmentally polluting, and completely destroys the silicon substrate, making it unrecyclable and significantly increasing manufacturing costs, thus unsuitable for mass production. The physical peeling method proposed in this application avoids the environmental pollution and safety hazards associated with chemical etching, and the growth substrate can be recycled and reused, significantly reducing manufacturing costs and making it suitable for mass production. This provides a feasible approach for the commercial application of flexible diamond devices.

[0039] In summary, the fabrication method of this application effectively solves many problems existing in diamond photodetectors in terms of flexibility, electrode performance and fabrication cost through a series of innovative technical means such as pre-positioning electrodes with patterned mask layers, using conductive carbon-based thin films as electrodes and physical stripping of substrates. It provides an efficient, environmentally friendly and high-performance solution for the fabrication of flexible all-carbon diamond photodetectors.

[0040] In some preferred embodiments, step S1 includes: S11. The growth substrate is ultrasonically cleaned sequentially using acetone, anhydrous ethanol and deionized water, and then dried. S12. A patterned mask layer is formed on the growth substrate based on photolithography.

[0041] Step S11 aims to efficiently remove various contaminants from the growth substrate surface through a synergistic effect of physical and chemical methods. Acetone, as a highly polar organic solvent, can effectively dissolve and remove organic residues such as grease and fingerprints from the growth substrate surface; anhydrous ethanol can further clean away acetone residues and other polar organic impurities; deionized water is used to rinse away the aforementioned solvent residues and water-soluble inorganic salts, ensuring a high level of cleanliness on the growth substrate surface. Ultrasonic cleaning generates cavitation effects in the liquid through high-frequency vibration, forming microbubbles that rapidly burst, thereby generating a powerful impact force. This impact force can penetrate deep into the microstructure of the growth substrate surface, peeling off particles and impurities attached to the growth substrate, thus significantly improving the cleaning effect. The purpose of drying the cleaned growth substrate is to remove residual cleaning solution from the surface of the growth substrate, avoiding adverse effects of moisture or solvent residues on the uniformity, adhesion, and exposure and development processes of subsequent photoresist spin coating. Common drying methods include purging with high-purity nitrogen or inert gas to remove surface liquid through airflow; or placing the growth substrate on a heating stage or oven for baking to accelerate liquid evaporation through heating.

[0042] Step S12 is used to precisely define the desired pattern on the surface of the growth substrate. The photolithography process transfers the preset pattern information from the mask to the photoresist layer, and then removes part of the photoresist through development, thereby forming a mask layer with a specific geometry and size on the surface of the growth substrate. This mask layer can precisely cover part of the top surface area of ​​the growth substrate and expose the remaining top surface area, providing a precise template for the subsequent localized growth of the first seed layer.

[0043] This approach ensures the cleanliness of the growth substrate surface through rigorous cleaning and drying pretreatment, providing an ideal foundation for subsequent photolithography processes. Based on this, a patterned mask layer is precisely fabricated using photolithography, effectively avoiding problems such as poor mask layer adhesion and pattern distortion caused by surface impurities. This refined pretreatment and patterning technique results in a more uniform distribution and more precise pattern of the seed crystals when forming the first seed layer on the exposed top surface of the growth substrate, thus guaranteeing the growth position and dimensional accuracy of the conductive carbon-based thin film. Combined with the basic method for fabricating flexible all-carbon diamond photodetectors, this approach significantly improves the reliability of the entire fabrication process and the performance consistency of the final device by providing a high-precision, high-stability patterned mask layer.

[0044] In some preferred embodiments, step S12 includes: S121. Photoresist is spin-coated onto a growth substrate using a photoresist spin-coating process to form a photoresist layer on the growth substrate, and then the photoresist layer is cured. S122. Expose the cured photoresist layer using a preset photomask. S123. The exposed photoresist layer is developed, and then the developed photoresist layer is rinsed with deionized water and dried in sequence; the developed photoresist layer is a patterned mask layer.

[0045] Photoresist spin coating is a method for uniformly coating a photoresist film onto a substrate surface. Its purpose is to ensure a uniform photoresist layer thickness, providing a stable foundation for subsequent exposure and development. Preferably, the parameters of the photoresist spin coating process in this embodiment are as follows: after coating the photoresist, the growth substrate is first rotated at 500 rpm for 5 seconds, and then rotated at 3000-4000 rpm for 30-60 seconds to ensure uniform distribution of the photoresist coated on the growth substrate, resulting in a photoresist layer of uniform thickness. The photoresist layer is the photosensitive material layer in the photolithography process. After exposure, it undergoes chemical changes, thereby forming the desired pattern during development. Photoresist layers can be classified into positive and negative photoresists based on their photosensitive properties. Curing treatment refers to heating or ultraviolet irradiation of the photoresist layer to evaporate the internal solvents and crosslink or polymerize the photoresist molecular chains, thereby enhancing the adhesion, hardness, and chemical stability of the photoresist layer. Curing treatment can be performed using methods such as thermal baking or ultraviolet curing. A pre-made photomask is a transparent or semi-transparent plate with a specific pattern, used to selectively block or allow light to pass through, thereby transferring the pattern onto the photoresist layer. The photomask can be pre-fabricated using high-precision methods such as electron beam etching or laser direct writing to create the desired pattern. Exposure processing refers to the process of transferring the pattern information from the photomask onto the photoresist layer using ultraviolet light or other radiation sources. Exposure processing changes the chemical properties of the irradiated areas of the photoresist layer, laying the foundation for subsequent development. Exposure equipment can include ultraviolet lithography machines, X-ray lithography machines, or electron beam exposure equipment. Development processing is the process of selectively dissolving the exposed or unexposed portions of the photoresist layer using a developer, thereby forming the desired pattern on the substrate. The type of developer depends on the type of photoresist used. Deionized water rinsing refers to rinsing the developed photoresist layer with high-purity deionized water to thoroughly remove residual developer and detached photoresist debris, preventing contamination or impact on subsequent processes. Drying refers to using high-purity gases, such as high-purity nitrogen, to blow away residual moisture from the substrate after rinsing, ensuring the substrate surface is dry. The patterned mask layer is a photoresist pattern formed on the growth substrate after the aforementioned photolithography process. Its function is to protect specific areas of the growth substrate while exposing areas requiring subsequent processing.

[0046] This solution ensures the precise formation of the patterned mask layer through a standardized photolithography process. First, a uniform photoresist layer is formed on the growth substrate using a spin-coating process and then cured. This ensures stable adhesion and consistent thickness between the photoresist layer and the growth substrate, providing a reliable foundation for subsequent pattern transfer. Next, the cured photoresist layer is exposed using a pre-set mask, accurately transferring the pre-defined precision pattern onto the photoresist layer. Finally, the photoresist is selectively removed through development, followed by rinsing with deionized water and drying to thoroughly remove any residue, ultimately forming a high-precision, sharp-edged, and impurity-free patterned mask layer. The synergistic effect of these steps allows the patterned mask layer formed on the growth substrate to precisely define the growth area of ​​the subsequent conductive carbon-based thin film, effectively avoiding the problem of the conductive carbon-based thin film shape not meeting design requirements due to mask layer defects. This significantly improves the fabrication yield and performance stability of the flexible all-carbon diamond photodetector.

[0047] In some preferred embodiments, the specific process of step S2 is the same as that of step S4, and step S2 includes: S21. Immerse the growth substrate with the patterned mask layer into a nanodiamond suspension; the nanodiamond suspension is composed of nanodiamond particles and solvent, and the particle size of the nanodiamond particles is 5-10 nm. S22. The growth substrate that has entered the nanodiamond suspension is subjected to ultrasonic treatment for a preset duration to form a first seed layer in the exposed top surface area of ​​the growth substrate.

[0048] The substrate to be implanted with crystals is immersed in a nanodiamond suspension. The nanodiamonds in the suspension directly provide the seed crystals needed for implantation, eliminating the need for additional complex equipment. This method is suitable for substrates with patterned masks or substrates with conductive carbon-based thin films, allowing for successful pre-arrangement of the seed crystals. A defined nanodiamond particle size range ensures uniform dispersion in the suspension, preventing agglomeration and guaranteeing uniform seed crystal distribution. This also meets the seed crystal size requirements for subsequent film growth, providing suitable nucleation sites for the growth of uniform and dense conductive carbon-based and flexible diamond films. The substrate immersed in the suspension is then ultrasonically treated. This ultrasonic treatment promotes uniform adhesion of nanodiamond particles to the substrate surface area requiring implantation, preventing seed crystal accumulation and ensuring better adhesion. This also prevents seed crystal detachment during subsequent processing, ensuring the stability of the seed layer. Ultimately, a seed layer meeting the requirements is obtained in the target area, satisfying the needs of subsequent film growth.

[0049] This scheme unifies the two-stage crystal implantation process, ensuring that the same operating steps and process parameters are used throughout the fabrication of flexible all-carbon diamond photodetectors, whether it's implanting a growth substrate with a patterned mask layer to form the first seed layer or implanting a growth substrate with a conductive carbon-based thin film to form the second seed layer. This unified implantation method ensures consistency and controllability in the seed layer formation process across different fabrication stages and substrate surface conditions. The growth substrate is immersed in a nanodiamond suspension, allowing for full contact between the substrate surface and the nanodiamond particles. The nanodiamond particles in the suspension serve as nucleation centers for diamond film growth, with a particle size limited to 5-10 nm. Particles within this size range have a high specific surface area, are easily dispersed uniformly, and are less prone to agglomeration, contributing to the formation of a high-density, uniform seed layer. Subsequently, the growth substrate immersed in the nanodiamond suspension undergoes ultrasonic treatment for a preset duration, using ultrasonic energy to promote the uniform adhesion of nanodiamond particles to the substrate surface. The cavitation effect and microjets generated by ultrasound can effectively disperse particles in the suspension and remove adsorbates from the substrate surface, thereby ensuring that the nanodiamond particles are uniformly attached to the exposed area of ​​the substrate and avoiding seed accumulation or uneven distribution. This uniform and optimized seeding process provides a stable and uniform nucleation basis for the subsequent growth of conductive carbon-based thin films and flexible diamond thin films, thus ensuring the performance and reliability of the final flexible all-carbon diamond photodetector.

[0050] In some preferred embodiments, step S3 includes: S31. Remove the graphical mask layer; S32. Using a first chemical vapor deposition process, a diamond film is grown on the top surface of the growth substrate based on the first seed layer, and diborane is introduced during the diamond film growth process to make the grown diamond film conductive, thereby forming a conductive carbon-based film on the top surface of the growth substrate.

[0051] In this embodiment, the patterned mask layer is preferably a patterned photoresist layer. This embodiment can employ chemical dissolution (e.g., immersing the growth substrate in acetone or a dedicated photoresist removal solution, combined with ultrasonic treatment) to dissolve and remove the patterned photoresist layer. The first chemical vapor deposition process is a technique for depositing diamond thin films on the surface of a growth substrate. This process, through a gas-phase reaction, induces carbon atoms to form a diamond crystal structure on the substrate surface under specific conditions. This process can be microwave plasma chemical vapor deposition (MPCVD). Diamond thin film growth based on a first seed layer on the top surface of the growth substrate refers to using a pre-precisely arranged first seed layer as nucleation points to guide the selective growth of the diamond thin film in the target area. Specifically, the first seed layer provides a high density of nucleation sites, enabling the diamond thin film to grow uniformly from these sites, forming a continuous and dense film, thereby ensuring the patterning accuracy and structural consistency of the conductive carbon-based thin film. The purpose of introducing diborane during diamond film growth is to achieve in-situ doping of the diamond film, giving it conductivity. Diborane, as a boron source, is introduced into the reaction chamber along with a carbon source and hydrogen during diamond growth. Boron atoms can replace carbon atoms in the diamond lattice to form p-type semiconductor diamond, thereby endowing it with conductivity. This in-situ doping method avoids complex subsequent doping processes and simplifies the preparation process. By introducing diborane during diamond film growth, the grown diamond film can be made conductive, thus enabling the diamond film to be used as the ohmic contact electrode of a flexible all-carbon diamond photodetector.

[0052] This scheme achieves precise fabrication of conductive carbon-based thin films through meticulous step design. First, by removing the patterned mask layer, excess seed crystals adsorbed on the mask layer are removed, ensuring that only the pre-defined electrode formation areas have seed crystals. This operation effectively avoids the growth of conductive structures in non-target areas, ensuring that the patterning accuracy of the conductive electrode meets design requirements. Second, using a first chemical vapor deposition process, diamond thin films are grown based on the first seed layer pre-positioned at the target location. The first seed layer acts as an efficient nucleation guide, making the growth position of the conductive carbon-based thin film more precise and the nucleation more uniform, thus ensuring the structural consistency of the patterned electrode and meeting the precision requirements of device fabrication. Furthermore, diborane is introduced in situ during the diamond thin film growth process, achieving doping of the diamond thin film and inherently endowing it with conductivity, allowing it to be used directly as an electrode without additional electrode processing steps, significantly simplifying the fabrication process. The resulting conductive carbon-based thin film, being a carbon-based material itself, shares the same carbon-based material as the subsequently grown flexible diamond film. This superior interfacial compatibility fundamentally solves the inherent defects of traditional metal electrodes, such as easy detachment, obstruction of incident light, and poor chemical stability, thus meeting the fabrication requirements of flexible all-carbon diamond photodetectors. This approach, combined with the overall fabrication method, ensures the precise formation and excellent performance of the conductive electrodes in the flexible all-carbon diamond photodetector, laying a solid foundation for realizing high-performance flexible photodetectors.

[0053] In some preferred embodiments, the reaction gases of the first chemical vapor deposition process are hydrogen and methane, the gas flow ratio of methane to hydrogen is 1%-5%, the ratio of diborane to methane is 2000-10000 ppm, the growth gas pressure of the first chemical vapor deposition process is 75 torr, and the growth temperature of the first chemical vapor deposition process is 900°C.

[0054] The reaction gases in the first chemical vapor deposition process are hydrogen and methane. Hydrogen typically serves as both a carrier gas and an etchant, effectively etching the non-diamond carbon phase during diamond growth to ensure the crystal quality of the grown film. Methane acts as a carbon source, providing the carbon atoms required for diamond growth. The methane to hydrogen gas flow rate ratio is 1%-5%, a key parameter controlling the diamond growth rate and film quality. Specifically, excessively high methane concentrations may lead to the formation of non-diamond carbon phases, affecting the film's conductivity and structural stability; conversely, excessively low methane concentrations will reduce the growth rate. The ratio of diborane to methane is 2000-10000 ppm. Diborane serves as a boron dopant source, imparting conductivity to the diamond film. This ratio determines the doping concentration of boron atoms, thus affecting the film's conductivity. Specifically, when the diborane-to-methane ratio is within this range, heavy doping can be achieved, resulting in a diamond film exhibiting metal-like conductivity. If the ratio is too low, the conductivity requirements of the electrode cannot be met; if the ratio is too high, it may disrupt the diamond lattice structure, affecting the film's mechanical properties and its adhesion to subsequent flexible diamond films. The growth gas pressure in the first chemical vapor deposition process is 75 torr. Growth gas pressure is a crucial parameter affecting plasma state, reactant transport, and the diamond growth mechanism. A pressure of 75 torr helps maintain a stable plasma and provides suitable thermodynamic conditions for diamond growth, thereby obtaining a dense and high-quality conductive carbon-based film. The growth temperature of the first chemical vapor deposition process is 900℃. The growth temperature directly affects the chemical reaction kinetics and the nucleation and growth process of diamond crystals. 900℃ is a commonly used optimized temperature for diamond film growth, which can promote the formation of high-quality diamonds, while inhibiting the formation of non-diamond carbon, ensuring the structural integrity and performance stability of the film.

[0055] This approach ensures that the grown conductive carbon-based thin film possesses the expected conductivity, excellent structural stability, and good adhesion to the subsequent flexible diamond thin film by precisely controlling various parameters of the first chemical vapor deposition process, including the type of reactant gas, gas flow ratio, doping ratio, growth pressure, and growth temperature. Specifically, hydrogen and methane are selected as reactant gases. Methane provides the carbon atoms required for diamond growth, while hydrogen effectively etches away the non-diamond phase generated during the growth process, ensuring the crystal structure quality of the conductive carbon-based thin film. Controlling the methane to hydrogen gas flow ratio within the range of 1%-5% ensures a suitable diamond growth rate, avoids the formation of amorphous carbon due to excessive carbon source, and prevents low growth efficiency due to insufficient carbon source. Meanwhile, by precisely controlling the ratio of diborane to methane within 2000-10000 ppm, the boron doping level was ensured to achieve the conductivity required for the carbon-based thin film, avoiding insufficient conductivity due to insufficient doping and excessive doping that could damage the original structure of the film and affect its adhesion to the subsequent diamond film. Furthermore, setting the growth pressure to 75 torr and the growth temperature to 900℃ provided a suitable thermodynamic environment for diamond growth, ensuring crystal growth quality and effectively avoiding film defects caused by unsuitable temperature or pressure parameters, thus ensuring the structural and performance stability of the conductive carbon-based thin film. The synergistic effect of these parameters enabled the formation of a high-quality conductive carbon-based thin film on the growth substrate. This film not only serves as the conductive electrode of the detector but also provides a stable foundation for the subsequent growth of flexible diamond films, ensuring that the flexible all-carbon diamond detector can be completely peeled from the growth substrate during physical exfoliation. This solves the problems of unstable performance and insufficient adhesion of conductive carbon-based thin films in traditional methods.

[0056] In some preferred embodiments, step S5 includes: S51. Using a second chemical vapor deposition process, diamond films are grown on the top surface of the growth substrate and the conductive carbon-based surface based on the second seed layer until the thickness of the diamond films grown on the top surface of the growth substrate and the conductive carbon-based surface reaches the preset thickness, so as to form a flexible diamond film on the top surface of the growth substrate and the conductive carbon-based surface.

[0057] The purpose of the second chemical vapor deposition process is to deposit a diamond film on a growth substrate that has already formed a conductive carbon-based thin film. This second chemical vapor deposition technique is preferably microwave plasma chemical vapor deposition (MPCVD), which provides high-density plasma and precise control of growth conditions. The second seed layer is a layer of nanodiamond particles pre-formed on the top surface of the growth substrate and the surface of the conductive carbon-based thin film. It serves as nucleation sites for the subsequent diamond film growth, providing uniform nucleation sites to ensure continuous, dense growth of the diamond film and coverage of the entire target area. Under the influence of the second seed layer, the diamond film grows simultaneously on the top surface of the growth substrate and the conductive carbon-based surface, ultimately forming a continuous whole. The preset thickness of the diamond film refers to the ideal thickness range of the diamond film pre-set according to the specific application requirements and performance indicators of the flexible diamond photodetector. This thickness needs to comprehensively consider the film's flexibility, mechanical strength, optical transmittance, and the convenience of subsequent peeling operations. Flexible diamond film refers to a diamond film with a certain thickness that can withstand bending, folding and other deformations, obtained through the above-mentioned growth process. This film has the inherent excellent physicochemical properties of diamond, such as high hardness, high thermal conductivity and wide bandgap, while also being flexible, which enables it to be applied in the field of flexible electronic devices. Its flexibility mainly comes from the control of the overall thickness of the film.

[0058] This scheme employs a second chemical vapor deposition (CVD) process for diamond film growth, which is compatible with the previous method of first seeding and then growing the diamond film. In step S4, a second seed layer is uniformly formed on the top surface of the growth substrate and the surface of the conductive carbon-based film. Based on this second seed layer, the second CVD process can provide uniform nucleation sites, allowing the diamond film to nucleate and grow simultaneously and uniformly on both the top surface of the growth substrate and the surface of the conductive carbon-based film. This synchronous growth mechanism ensures that the final flexible diamond film can integrally cover the conductive carbon-based film and fill the gaps between them, thus forming a continuous and dense monolithic structure. By continuously growing the diamond film until the thickness reaches the preset thickness, the mechanical properties of the film can be precisely controlled. The appropriate thickness ensures that the diamond film has both sufficient toughness to meet the bending deformation requirements of flexible devices and sufficient structural strength to prevent damage during subsequent operations (such as physical peeling). This controlled growth method, combined with the formation of conductive carbon-based thin films in the preceding steps, ultimately achieves a strong bond between the flexible diamond film and the conductive carbon-based film, forming a flexible all-carbon diamond photodetector, and ensuring that the detector can be physically peeled off completely and smoothly from the growth substrate.

[0059] In some preferred embodiments, the reaction gases for the second chemical vapor deposition include oxygen, hydrogen, and methane, with a methane to hydrogen gas flow rate ratio of 0.5%-3%, a growth gas pressure of 75 torr for the second chemical vapor deposition process, a growth temperature of 900°C for the second chemical vapor deposition process, and a preset thickness of 1-20 μm.

[0060] The introduction of oxygen selectively etches away non-diamond phase carbon impurities generated during diamond deposition, significantly improving the purity and crystallinity of the flexible diamond film. The methane to hydrogen gas flow rate ratio is 0.5%-3%, a crucial parameter in diamond chemical vapor deposition that directly affects the diamond growth rate, crystallinity, and the formation of non-diamond phase carbon. Specifically, if the methane ratio is too low, the diamond growth rate will be very slow, or even difficult to nucleate; if the methane ratio is too high, a large amount of non-diamond phase carbon (such as graphite) will easily form, leading to a decrease in film quality. Therefore, controlling this ratio within the range of 0.5%-3% effectively balances the growth rate and film quality. The preset thickness is 1-20 μm. The thickness of the flexible diamond film is a key parameter determining its flexibility, mechanical strength, and adhesion to the growth substrate. Limiting the thickness to the range of 1-20 μm ensures that the diamond film possesses sufficient flexibility to meet the deformation requirements of flexible devices, avoiding excessive rigidity due to excessive thickness that would prevent bending. Simultaneously, this thickness range also guarantees sufficient mechanical strength, preventing damage due to excessive thinness. Furthermore, this thickness meets the adhesion requirements of subsequent physical peeling steps, ensuring the detector can be successfully peeled from the growth substrate.

[0061] This solution ensures the growth of a qualified flexible diamond film by clearly defining and reasonably limiting the second chemical vapor deposition (CVD) process parameters and the final film thickness. This guarantees the production of a suitable flexible diamond film that meets the requirements for subsequent stripping and detector use. Oxygen, hydrogen, and methane are selected as the reactants for the second CVD. The introduction of oxygen can etch away non-diamond carbon impurities generated during diamond deposition, significantly improving the purity and crystallinity of the flexible diamond film. This enhances the flexibility of the diamond film and ensures good photoelectric performance for the detector. Limiting the methane to hydrogen flow rate within a specified range of 0.5%-3% ensures a suitable diamond growth rate without generating excessive non-diamond carbon impurities due to excessive methane content, thus guaranteeing the growth quality of the diamond film. The thickness of the flexible diamond film is limited to a specified range of 1-20 μm. Within this thickness range, the diamond film ensures sufficient flexibility to meet the deformation requirements of flexible devices, avoiding excessive rigidity due to excessive thickness and inability to bend, while also avoiding insufficient mechanical strength and easy breakage due to insufficient thickness. At the same time, this thickness also meets the requirements for adhesion, ensuring that the detector can be successfully physically peeled off from the growth substrate, thus improving the device fabrication yield. Through the synergistic control of the above parameters, the flexible diamond film formed on the top surface of the growth substrate and the surface of the conductive carbon-based film has excellent crystal quality, suitable flexibility, and moderate adhesion to the growth substrate, thus providing favorable conditions for the subsequent physical peeling step and ultimately obtaining a high-performance flexible all-carbon diamond photodetector.

[0062] In some preferred embodiments, step S6 includes: S61. Adhesive flexible carrier is attached to the surface of flexible diamond film; S52. Air bubbles between the flexible carrier and the flexible diamond film are expelled by gently pressing the flexible carrier. S53. Apply mechanical force to the flexible carrier to peel the flexible all-carbon diamond detector off the growth substrate.

[0063] A viscous flexible carrier is a material with inherent flexibility and adhesive properties. Its function is to act as a force-bearing medium during the peeling process, uniformly transferring mechanical force to the flexible diamond film and providing sufficient adhesion to ensure complete peeling. Viscous flexible carriers can be heat-release tapes, PDMS (polydimethylsiloxane) films, Kapton tape, or transparent PET (polyethylene terephthalate) tape. Adhering the flexible carrier to the surface of the flexible diamond film ensures a tight contact, providing a reliable physical bond for subsequent peeling operations. Gently pressing the flexible carrier to remove air bubbles between the carrier and the flexible diamond film aims to eliminate air gaps at the interface, ensuring complete adhesion and uniform distribution of adhesive force. Specifically, a soft roller can be used to slowly roll on the surface of the flexible carrier, pushing air bubbles from the center to the edges; alternatively, a soft scraper can be used to gently scrape the surface of the flexible carrier, squeezing out the air bubbles. Applying mechanical force to a flexible carrier to peel the flexible all-carbon diamond detector from the growth substrate provides the energy needed to overcome the bonding force between the flexible diamond film and the growth substrate, thereby achieving the physical peeling of the flexible all-carbon diamond detector. The mechanical force can be applied manually, where an operator holds the flexible carrier and peels it off the growth substrate at a certain angle and speed; or it can be applied using automated peeling equipment, utilizing a robotic arm or automated platform to achieve stable and reliable peeling by precisely controlling the peeling angle, speed, and force.

[0064] This method employs a standardized physical peeling process to smoothly and completely peel the flexible all-carbon diamond detector from the growth substrate. Specifically, firstly, a flexible carrier with adhesive properties is selected as the force-bearing medium. Its flexibility adapts to the surface morphology of the flexible diamond film, ensuring close contact with the entire film surface during bonding. Simultaneously, its adhesiveness provides sufficient adhesion to firmly fix the flexible diamond film onto the carrier. Secondly, by gently pressing the flexible carrier, air bubbles are expelled, eliminating gaps between the flexible carrier and the flexible diamond film. This ensures complete adhesion between the flexible carrier and the device surface, allowing the adhesive force to be evenly distributed across the entire device surface. This avoids localized poor adhesion or uneven stress caused by gaps, effectively preventing device breakage or incomplete peeling during the process. Finally, mechanical force is applied to the flexible carrier to complete the peeling. Since the bonding force between the flexible diamond film and the conductive carbon-based film is greater than the bonding force between the flexible diamond film and the growth substrate, and also greater than the bonding force between the conductive carbon-based film and the growth substrate, this means that the internal structure (the flexible diamond film and the conductive carbon-based film) of the flexible all-carbon diamond detector as a whole has a higher bonding strength than its interface bonding strength with the growth substrate. Therefore, when mechanical force is uniformly applied to the flexible diamond film through the flexible carrier, peeling will only occur at the interface between the flexible all-carbon diamond detector and the growth substrate, thus achieving complete physical peeling of the entire detector. The entire peeling process is a physical process, without the use of polluting acids or damage to the growth substrate, facilitating substrate recycling and reuse, reducing manufacturing costs, and adapting to the needs of mass production.

[0065] Secondly, this application also provides a flexible all-carbon diamond photodetector, which is prepared by the flexible all-carbon diamond photodetector preparation method provided in the first aspect above.

[0066] The flexible all-carbon diamond photodetector provided in this embodiment is prepared by the flexible all-carbon diamond photodetector preparation method provided in the first aspect above. The principle of the flexible all-carbon diamond photodetector provided in this embodiment is the same as that of the flexible all-carbon diamond photodetector preparation method provided in the first aspect above, and will not be repeated here.

[0067] As can be seen from the above, the flexible all-carbon diamond photodetector and its fabrication method provided in this application use an all-carbon structure to replace the traditional metal electrodes and a physical exfoliation process to replace the traditional chemical etching process. The process sequentially completes the steps of patterned mask preparation, crystal implantation, conductive carbon-based thin film growth, secondary crystal implantation, flexible diamond thin film growth, and physical exfoliation, thereby obtaining a structurally stable flexible all-carbon diamond photodetector. This method solves the problems of easy detachment and breakage of traditional metal electrodes and poor chemical stability, as well as the problems of high pollution, non-recyclable substrates, high cost, high processing difficulty, and low yield associated with traditional chemical etching methods. It has the advantages of good structural stability, long service life, green and pollution-free operation, low fabrication cost, high device yield, and can meet the requirements of flexible electronic devices that can be bent and deformed.

[0068] In the embodiments provided in this application, it should be understood that relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0069] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for fabricating a flexible all-carbon diamond photodetector, characterized in that, The method for fabricating the flexible all-carbon diamond photodetector includes the following steps: S1. A patterned mask layer is formed on a growth substrate; the patterned mask layer is used to cover a portion of the top surface area of ​​the growth substrate and expose the remaining top surface area of ​​the growth substrate. S2. Perform a seeding process on the growth substrate to form a first seed layer in the exposed top surface region of the growth substrate; S3. Remove the patterned mask layer, and then grow a conductive carbon-based thin film on the top surface of the growth substrate based on the first seed layer; S4. Perform a secondary seeding process on the growth substrate on which the conductive carbon-based thin film is grown, so as to form a second seed layer on the top surface of the growth substrate and the surface of the conductive carbon-based thin film. S5. A flexible diamond film is grown on the top surface of the growth substrate and the conductive carbon-based surface based on the second seed layer; the flexible diamond film and the conductive carbon-based film form a flexible all-carbon diamond photodetector, and the bonding force between the flexible diamond film and the conductive carbon-based film is greater than the bonding force between the flexible diamond film and the growth substrate and the bonding force between the conductive carbon-based film and the growth substrate. S6. Physically peel the flexible all-carbon diamond detector from the growth substrate.

2. The method for fabricating a flexible all-carbon diamond photodetector according to claim 1, characterized in that, Step S1 includes: S11. The growth substrate is ultrasonically cleaned sequentially using acetone, anhydrous ethanol and deionized water, and then dried. S12. A patterned mask layer is formed on the growth substrate based on a photolithography process.

3. The method for fabricating a flexible all-carbon diamond photodetector according to claim 2, characterized in that, Step S12 includes: S121. Photoresist is spin-coated onto the growth substrate using a photoresist spin-coating process to form a photoresist layer on the growth substrate, and then the photoresist layer is cured. S122. Expose the cured photoresist layer using a preset photomask. S123. The exposed photoresist layer is developed, and then the developed photoresist layer is rinsed with deionized water and dried in sequence; the developed photoresist layer is a patterned mask layer.

4. The method for fabricating a flexible all-carbon diamond photodetector according to claim 1, characterized in that, The specific process of step S2 is the same as that of step S4. Step S2 includes: S21. Immerse the growth substrate with the patterned mask layer into a nanodiamond suspension; the nanodiamond suspension is composed of nanodiamond particles and a solvent, and the nanodiamond particles have a particle size of 5-10 nm. S22. The growth substrate that has entered the nanodiamond suspension is subjected to ultrasonic treatment for a preset duration to form a first seed layer in the exposed top surface region of the growth substrate.

5. The method for fabricating a flexible all-carbon diamond photodetector according to claim 1, characterized in that, Step S3 includes: S31. Remove the graphical mask layer; S32. Using a first chemical vapor deposition process, a diamond film is grown on the top surface of the growth substrate based on the first seed layer, and diborane is introduced during the diamond film growth process to make the grown diamond film conductive, thereby forming a conductive carbon-based film on the top surface of the growth substrate.

6. The method for fabricating a flexible all-carbon diamond photodetector according to claim 5, characterized in that, The reaction gases in the first chemical vapor deposition process are hydrogen and methane, the gas flow ratio of methane to hydrogen is 1%-5%, the ratio of diborane to methane is 2000-10000 ppm, the growth gas pressure of the first chemical vapor deposition process is 75 torr, and the growth temperature of the first chemical vapor deposition process is 900℃.

7. The method for fabricating a flexible all-carbon diamond photodetector according to claim 1, characterized in that, Step S5 includes: S51. Using a second chemical vapor deposition process, diamond films are grown on the top surface of the growth substrate and the conductive carbon-based surface based on the second seed layer until the thickness of the diamond films grown on the top surface of the growth substrate and the conductive carbon-based surface reaches a preset thickness, so as to form a flexible diamond film on the top surface of the growth substrate and the conductive carbon-based surface.

8. The method for fabricating a flexible all-carbon diamond photodetector according to claim 7, characterized in that, The reaction gases for the second chemical vapor deposition include oxygen, hydrogen, and methane, with a methane to hydrogen gas flow rate ratio of 0.5%-3%. The growth gas pressure for the second chemical vapor deposition process is 75 torr, the growth temperature for the second chemical vapor deposition process is 900℃, and the preset thickness is 1-20 μm.

9. The method for fabricating a flexible all-carbon diamond photodetector according to claim 1, characterized in that, Step S6 includes: S61. Adhesive flexible carrier is attached to the surface of the flexible diamond film; S52. Air bubbles between the flexible carrier and the flexible diamond film are expelled by gently pressing the flexible carrier. S53. Apply mechanical force to the flexible carrier to peel the flexible all-carbon diamond detector off the growth substrate.

10. A flexible all-carbon diamond photodetector, characterized in that, The flexible all-carbon diamond photodetector is prepared by the method for preparing a flexible all-carbon diamond photodetector as described in any one of claims 1-9.

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